1. Field of the Invention
This invention relates to simulation apparatus and, more particularly, to apparatus for simulating signals suitable for simulating operational sonar equipment. In most undersea work, the ships, submersibles, etc., contain sonar equipment which enable the operators to listen in on the environment. Under water, listening is almost as important as seeing is above water. The listening equipment can produce signals which indicate the direction from which distant sounds are coming and can distinguish between coherent sound sources and the random noise of the sea. The operation of such sonar equipment can be quite complex and, for best performance of the system, the operator should be carefully a completely tranied. To train such operators, simulators are often used. The simulators duplicate the generation of the actual sounds under the control of an instructor without requiring that actual sound sources be present. In this manner, the equipment can duplicate a number of sound sources to train the operators in recognizing the various sources and can vary the direction from the trainee of the different sources so that the trainee is taught to use his equipment.
2. The Prior Art
In general sonar simulators of the prior art were analog systems for the most part. It was only recently that digital systems for the simulation of sonar systems became generally utilized. Analog systems are not readily controlled by digital computers, and such computers are the core of most modern simulators. In addition, past sonar simulators have simulated a large portion, if not all, of the operation sonar system. This produced systems which are large and expensive.